SIRIUS reversing starter with AS-Interface bus
The Siemens SIRIUS 3RK4320-3BR51-1BA0 is a reversing motor starter designed for motor control applications requiring forward/reverse operation. It integrates the contactor, overload relay, and reversing interlock into a single compact unit, communicating over AS-Interface for direct integration with higher-level control systems. The Trip Class 10 bimetal overload protection ensures the motor is disconnected before winding damage occurs during a stalled-rotor condition.
IP55 enclosure and mounting flexibility
The enclosure is not submersible but handles splashing and condensation without internal damage. Dimensions of 145 mm depth, 182 mm width, and 220 mm height fit standard enclosure layouts with room for adjacent devices. The control supply accepts 20.4 to 26.4 V DC, matching standard 24 V DC industrial power supplies.
Active production and sourcing posture
The unit supports AS-Interface protocol (AS-i) for communication, reducing point-to-point wiring compared to conventional parallel-wired starters. It does not support PROFIBUS DP or PROFINET, so network integration requires an AS-i gateway if the control system uses those fieldbuses. Ambient temperature range of -25 to +35 °C limits installation to climate-controlled or moderate environments; derating may apply above 35 °C. The bimetal overload is non-adjustable for trip class, so coordination with upstream short-circuit protection (circuit-breakers) must follow the manufacturer's selectivity tables.